Phase difference plate for organic el display device, organic el display device, and method for producing phase difference plate

ABSTRACT

An object of the present invention is to provide a phase difference plate for an organic EL display device having excellent light resistance, an organic EL display device, and a method for producing a phase difference plate. The phase difference plate for an organic EL display device of an embodiment of the present invention has a phase difference layer formed from a composition containing a polymer having a repeating unit A including a photo-alignment group and a polymerizable liquid crystal compound having reciprocal wavelength dispersion, in which the photo-alignment group includes a double bond structure of C═C or C═N.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2018/023483 filed on Jun. 20, 2018, which claims priority under 35U.S.C. § 119(a) to Japanese Patent Application No. 2017-121590 filed onJun. 21, 2017. The above application is hereby expressly incorporated byreference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a phase difference plate for an organicEL display device, an organic EL display device, and a method forproducing a phase difference plate.

2. Description of the Related Art

It is known that a circularly polarizing plate is used as anantireflection film so as to reduce the reflection of external light ona display surface in an image display device such as an organicelectroluminescence (EL) display device.

As such a circularly polarizing plate, for example, an aspect in which a¼ wavelength plate (λ/4 plate) and a polarizer are combined as describedin JP1997-127885A (JP-H09-127885A) is known.

SUMMARY OF THE INVENTION

In recent years, a further improvement in optical characteristicsrequired for an antireflection film has been demanded, and a controlover a three-dimensional refractive index distribution defined as an Nzfactor has become very important. It is considered that among those, aphase difference plate satisfying 0<Nz<1 can be suitably applied toantireflection film applications of an organic EL display device. Forexample, it is considered that a phase difference plate satisfyingNz=0.5 has a substantially constant phase difference value regardless ofa viewing angle, and it is possible to significantly improve the viewingangle characteristics of an antireflection film using such a phasedifference plate.

Under such circumstances, the present inventors have made an attempt toapply the phase difference plate described in JP2016-080942A as anantireflection film of an organic EL display device, and have thusrevealed that the light resistance of the phase difference plate appliedis deteriorated in some cases, depending on the type of a rod-likeliquid crystalline compound or the type of a functional group(photo-alignment group) contained in a high molecular compound.

Therefore, an object of the present invention is to provide a phasedifference plate for an organic EL display device having excellent lightresistance, an organic EL display device, and a method for producing aphase difference plate.

The present inventors have conducted extensive studies to accomplish theobject, and as a result, they have found that the light resistance of aphase difference layer formed is improved by using a polymer having arepeating unit A including a specific photo-alignment group and apolymerizable liquid crystal compound having reciprocal wavelengthdispersion in combination, thereby completing the present invention.

That is, the present inventors have found that the object can beaccomplished by the following configurations.

[1] A phase difference plate for an organic EL display device,comprising a phase difference layer formed from a composition containinga polymer having a repeating unit A including a photo-alignment groupand a polymerizable liquid crystal compound having reciprocal wavelengthdispersion,

in which the photo-alignment group includes a double bond structure ofC═C or C═N.

[2] The phase difference plate for an organic EL display device asdescribed in [1],

in which the photo-alignment group is a cinnamate group or a chalconegroup.

[3] The phase difference plate for an organic EL display device asdescribed in [1] or [2],

in which the polymerizable liquid crystal compound having reciprocalwavelength dispersion is a liquid crystal compound represented byFormula (3) which will be described later.

[4] The phase difference plate for an organic EL display device asdescribed in any one of [1] to [3],

in which the polymer is an acrylic or methacrylic polymer.

[5] The phase difference plate for an organic EL display device asdescribed in any one of [1] to [4],

in which the phase difference layer satisfies Formula (I),

Re(450)≤Re(550)≤Re(650)  (1)

in Formula (I), Re(450) represents an in-plane retardation valuemeasured at a wavelength of 450 nm, Re(550) represents an in-planeretardation value measured at a wavelength of 550 rim, and Re(650)represents an in-plane retardation value measured at a wavelength of 650nm.

[6] The phase difference plate for an organic EL display device asdescribed in any one of [1] to [5],

in which the phase difference layer is a layer indicating an in-planeretardation value measured at a wavelength of 550 nm of 100 to 180 nm.

[7] The phase difference plate for an organic EL display device asdescribed in any one of [1] to [6],

in which the phase difference layer is a layer indicating athickness-direction retardation value measured at a wavelength of 550 nmof −10 to 10 nm.

[8] The phase difference plate for an organic EL display device asdescribed in any one of [1] to [7],

in which the phase difference layer satisfies a refractive indexrelationship represented by Formula (II),

nx>nz>ny  (II)

in Formula (II), nx is a refractive index in a direction in which arefractive index is maximum in a plane, ny is a refractive index in adirection in which a refractive index is minimum in a plane, and nzrepresents a refractive index in a thickness direction perpendicular tonx and ny.

[9] The phase difference plate for an organic EL display device asdescribed in any one of [1] to [8],

in which the phase difference layer satisfies Formula (III),

0.4<(nx−nz)/(nx−ny)<0.6  (III)

in Formula (III), nx is a refractive index in a direction in which arefractive index is maximum in a plane, ny is a refractive index in adirection in which a refractive index is minimum in a plane, and nzrepresents a refractive index in a thickness direction perpendicular tonx and ny.

[10] The phase difference plate for an organic EL display device asdescribed in any one of [1] to [9],

in which the phase difference layer is a monolayer structure.

[11] An organic EL display device comprising:

the phase difference plate for an organic EL display device as describedin any one of [1] to [10]; and

an organic EL light emitting element.

[12] A method for producing a phase difference plate, used for themanufacture of the phase difference plate for an organic EL displaydevice as described in any one of [1] to [10], the method comprising:

an applying step of applying a composition containing a polymer having arepeating unit A including a photo-alignment group including a doublebond structure of C═C or C═N and a polymerizable liquid crystal compoundhaving reciprocal wavelength dispersion onto a transparent support toform a coating film;

an irradiating step of performing irradiation with polarized ultravioletrays from a direction perpendicular to the coating film; and

a heating step of subjecting the coating film to a heating treatmentafter the irradiating step to form a phase difference layer.

According to the present invention, it is possible to provide a phasedifference plate for an organic EL display device having excellent lightresistance, an organic EL display device, and a method for producing aphase difference plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in detail.

Description of configuration requirements described below may be made onthe basis of representative embodiments of the present invention in somecases, but the present invention is not limited to such embodiments.

Furthermore, in the present specification, a numerical value rangeexpressed using “to” is used in a meaning of a range that includes thepreceding and succeeding numerical values of “to” as the lower limitvalue and the upper limit value, respectively.

In addition, in the present specification, the bonding direction of adivalent group (for example, —O—CO—) denoted is not particularlylimited, and for example, in a case where D¹ in Formula (3) which willbe described later is —O—CO—, a position bonding to the Ar side isdefined as *1, and a position bonding to the G¹ side is defined as *2,D¹ may be either *1-O—CO—*2 or *1-CO—O—*2.

[Phase Difference Plate for Organic EL Display Device]

The phase difference plate for an organic EL display device of anembodiment of the present invention (hereinafter also simply referred toas “the phase difference plate of the embodiment of the presentinvention”) has a phase difference layer formed from a composition(hereinafter also simply referred to as a “specific composition”)containing a polymer (hereinafter also simply referred to as a “specificpolymer”) having a repeating unit A including a photo-alignment groupand a polymerizable liquid crystal compound having reciprocal wavelengthdispersion,

In addition, the photo-alignment group included in the repeating unit Aincludes a double bond structure of C═C or C═N.

In the present invention, the light resistance is improved byincorporation of a phase difference layer formed from a specificcomposition containing a specific polymer having a repeating unit Aincluding a photo-alignment group including a double bond structure ofC═C or C═N and a polymerizable liquid crystal compound having reciprocalwavelength dispersion, as described above.

Details thereof are not clear, but are presumed as follows by thepresent inventors.

That is, it is possible to express desired optical characteristics,specifically biaxial phase difference having reciprocal wavelengthdispersion, by allowing a polymer having a repeating unit A including aspecific photo-alignment group to contribute to the alignment of thepolymerizable liquid crystal compound having reciprocal wavelengthdispersion. At this time, by using a specific polymer having a repeatingunit A including a photo-alignment group including a double bondstructure of C═C or C═N in combination, the photo-alignment group or aphotoreactive substance thereof can have absorptivity at a shorter wavethan the light emitting spectrum of an organic EL light emittingelement, and therefore, even in a case where the phase difference plateis used in applications as an antireflection film in an organic ELdisplay device having a high light emission intensity from an organic ELlight emitting element, it is possible to maintain a desired alignmentstate while suppressing deterioration due to light irradiation, wherebythe durability is improved.

[Specific Composition]

The phase difference layer contained in the phase difference plate ofthe embodiment of the present invention is formed from a specificcomposition containing a specific polymer having a repeating unit Aincluding a photo-alignment group including a double bond structure ofC═C or C═N and a polymerizable liquid crystal compound having reciprocalwavelength dispersion, as described above.

<Specific Polymer>

(Repeating Unit A)

The repeating unit A contained in the specific polymer is a repeatingunit including a photo-alignment group including a double bond structureof C═C or C═N, and examples thereof include a repeating unit representedby Formula (1) or (2).

In Formulae (1) and (2), R represents a hydrogen atom or an alkyl grouphaving 1 to 6 carbon atoms, L represents a divalent linking group, and Prepresents a photo-alignment group including a double bond structure ofC═C or C═N.

Here, in Formulae (1) and (2), R is preferably a hydrogen atom or analkyl group having 1 to 4 carbon atoms (for example, a methyl group, anethyl group, an n-propyl group, an isopropyl group, and an n-butylgroup), and among these, and the hydrogen atom or the methyl group ismore preferable.

Moreover, the double bond structure of C═C or C═N represented by P inFormulae (1) and (2) is preferably a trans type rather than a cis type,and more preferably a trans type C═C.

Specific suitable examples of such a photo-alignment group including adouble bond structure include a cinnamate group, a chalcone group, and amaleimido group; and among these, the cinnamate group or the chalconegroup is preferable, and the cinnamate group is more preferable, for areason that the group has a high sensitivity to polarized ultravioletrays and thus, the light resistance of a phase difference plate thusobtained is further improved.

In the present invention, as long as the double bond structure of C═C orC═N represented by P in Formulae (1) and (2) may have a substituent aslong as the structure does not lose photo-alignment properties. Specificexamples of the substituent include a hydroxyl group, a carboxyl group,a halogen atom, a linear, branched, or cyclic alkyl group having 1 to 20carbon atoms, a linear halogenated alkyl group having 1 to 20 carbonatoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group having6 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, acyano group, and an amino group. Incidentally, a proton of the carboxylgroup may be dissociated or combined with a counterion (for example, analkali metal ion) to form the state of a salt.

Examples of the halogen atom as the substituent include a fluorine atom,a chlorine atom, a bromine atom, and an iodine atom, and among these,the fluorine atom or the chlorine atom is preferable.

With regard to the linear, branched, or cyclic alkyl group having 1 to20 carbon atoms as the substituent, as the linear alkyl group, an alkylgroup having 1 to 6 carbon atoms is preferable, and specific examplesthereof include a methyl group, an ethyl group, and an n-propyl group.

As the branched alkyl group, an alkyl group having 3 to 6 carbon atomsis preferable, and specific examples thereof include an isopropyl groupand a tert-butyl group.

As the cyclic alkyl group, an alkyl group having 3 to 6 carbon atoms ispreferable, and specific examples thereof include a cyclopropyl group, acyclopentyl group, and a cyclohexyl group.

As the linear halogenated alkyl group having 1 to 20 carbon atoms as thesubstituent, a fluoroalkyl group having 1 to 4 carbon atoms ispreferable, specific examples thereof include a trifluoromethyl group, aperfluoroethyl group, a perfluoropropyl group, and a perfluorobutylgroup, and among these, the trifluoromethyl group is preferable.

As the alkoxy group having 1 to 20 carbon atoms as the substituent, analkoxy group having 1 to 8 carbon atoms is preferable, specific examplesthereof include a methoxy group, an ethoxy group, an n-butoxy group, anda methoxyethoxy group, and among these, the methoxy group or the ethoxygroup is preferable.

As the aryl group having 6 to 20 carbon atoms as the substituent, anaryl group having 6 to 12 carbon atoms is preferable, specific examplesthereof include a phenyl group, an O-methylphenyl group, and a naphthylgroup, and among these, the phenyl group is preferable.

As the aryloxy group having 6 to 20 carbon atoms as the substituent, anaryloxy group having 6 to 12 carbon atoms is preferable, specificexamples thereof include a phenyloxy group and a 2-naphthyloxy group,and among these, the phenyloxy group is preferable.

Examples of the amino group as the substituent include a primary aminogroup (—NH₂); a secondary amino group such as a methylamino group; and atertiary amino group such as a dimethylamino group, a diethylaminogroup, a dibenzylamino group, and a group having the nitrogen atom of anitrogen-containing heterocyclic compound (for example, pyrrolidine,piperidine, and piperazine) as a bond.

Furthermore, examples of the divalent linking group represented by L inFormulae (1) and (2) include a divalent linking group formed bycombination of at least two or more groups selected from the groupconsisting of a linear, branched, or cyclic alkylene group having 1 to10 carbon atoms, which may have a substituent, an arylene group having 6to 12 carbon atoms, which may have a substituent, an ether group (—O—),a carbonyl group (—C(═O)—), and an imino group (—NH—) which may have asubstituent.

Here, examples of the substituent which may be contained in each of thealkylene group, the arylene group, and the imino group include an alkylgroup, an alkoxy group, a halogen atom, and a hydroxyl group.

As the alkyl group, for example, a linear, branched, or cyclic alkylgroup having 1 to 18 carbon atoms is preferable, an alkyl group having 1to 8 carbon atoms (for example, a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, asec-butyl group, a t-butyl group, and a cyclohexyl group) is morepreferable, an alkyl group having 1 to 4 carbon atoms is still morepreferable, and the methyl group or the ethyl group is particularlypreferable.

As the alkoxy group, for example, an alkoxy group having 1 to 18 carbonatoms is preferable, an alkoxy group having 1 to 8 carbon atoms (forexample, a methoxy group, an ethoxy group, an n-butoxy group, and amethoxyethoxy group) is more preferable, an alkoxy group having 1 to 4carbon atoms is still more preferable, and the methoxy group or theethoxy group is particularly preferable.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom, and an iodine atom, and among these, the fluorine atom orthe chlorine atom is preferable.

With regard to the linear, branched, or cyclic alkylene group having 1to 10 carbon atoms, specific examples of the linear alkylene groupinclude a methylene group, an ethylene group, a propylene group, abutylene group, a pentylene group, a hexylene group, and a decylenegroup.

Moreover, specific examples of the branched alkylene group include adimethylmethylene group, a methylethylene group, a 2,2-dimethylpropylenegroup, and a 2-ethyl-2-methylpropylene group.

In addition, specific examples of the cyclic alkylene group include acyclopropylene group, a cyclobutylene group, a cyclopentylene group, acyclohexylene group, a cyclooctylene group, a cyclodecylene group, anadamantane-diyl group, a norbonane-diyl group, and anexo-tetrahydrodicyclopentadiene-diyl group, and among these, thecyclohexylene group is preferable.

Specific examples of the arylene group having 6 to 12 carbon atomsinclude a phenylene group, a xylylene group, a biphenylene group, anaphthylene group, and a 2,2′-methylenebisphenyl group, and among these,the phenylene group is preferable.

In the present invention, L in Formulae (1) and (2) is preferably adivalent linking group including at least an arylene group having 6 to12 carbon atoms, which may have a substituent, and more preferably adivalent linking group including at least a linear alkylene group having1 to 10 carbon atoms, which may have a substituent, and an arylene grouphaving 6 to 12 carbon atoms, which may have a substituent.

Moreover, in the present invention, L in Formulae (1) and (2) ispreferably a divalent linking group including a mesogen group.

Here, suitable examples of the mesogen group include a group representedby (MG-I).

-(Q¹¹Z¹¹)_(k)-(Q¹²-Z¹²)_(l)-Q¹⁵-(Z¹³Q¹³)_(m)-(Q¹⁴-Z¹⁴)_(n)—  MG-I:

In the formula, Q¹¹, Q¹², Q¹³, Q¹⁴, and Q¹⁵ each independently representa 1,4-phenylene group (hereinafter also referred to as a “benzenering”), a heterocyclic group obtained by substituting one or two or moreCH groups of a 1,4-phenylene group with N, a 1,4-cyclohexylene group(hereinafter also referred to as a “cyclohexane ring”), a heterocyclicgroup obtained by optionally substituting one CH₂ group or twonon-adjacent CH₂ groups of a 1,4-cyclohexylene group with O and/or S, a1,4-cyclohexenylene group, or a naphthalene-2,6-diyl group. These groupsmay have a substituent. Among those, it is preferable that Q¹⁵ is abenzene ring, and Q¹¹, Q¹², Q¹³, and Q¹⁴ are each independently abenzene ring or a cyclohexane ring from the viewpoint of cost and thelike.

In addition, in the formula, Z¹¹, Z¹², Z¹³, and Z¹⁴ each independentlyrepresent —COO—, —OCO—, —COOCH₂CH₂—, —CH₂CH₂CO—, —CH₂CH₂—, —OCH₂—,—CH₂O—, —CH═CH—, —C═C—, —CH═CH—COO—, —OCO—CH═CH—, —NH═CH₂—, —CH₂═NH—,—SCO—, —OCS—, or a single bond. Among these, —COO—, —OCO—, —COOCH₂CH₂—,or —CH₂CH₂OCO— is preferable from the viewpoint of cost and the like.

In addition, in the formula, k, l, m, and n are each independently aninteger of 0 to 2.

Furthermore, in the present invention, as the repeating unit A includinga photo-alignment group including a double bond structure of C═C or C═N,the repeating unit represented by Formula (1) is preferable, and arepeating unit represented by Formula (1a) or (1b) including a cinnamategroup as a photo-alignment group is more preferable, among the repeatingunits represented by Formulae (1) and (2).

In Formulae (1a) and (1b), R and L are both the same as those describedin Formula (1).

In addition, R¹¹ to R¹⁵ in Formula (1a) and R¹⁶ in Formula (1b) eachindependently represent a hydrogen atom or a substituent. In R¹¹, R¹²,R¹³, R¹⁴, and R¹⁵, two adjacent groups may be bonded to each other toform a ring. Further, among R¹¹, R¹², R¹³, R¹⁴, and R¹⁵, R¹³ in thepara-position is preferably a substituent. Further, examples of thesubstituent include a hydroxyl group, a carboxyl group, a halogen atom,a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, alinear halogenated alkyl group having 1 to 20 carbon atoms, an alkoxygroup having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbonatoms, an aryloxy group having 6 to 20 carbon atoms, a cyano group, andan amino group, which are exemplified as a substituent which may becontained in the photo-alignment group.

In addition, in Formula (1b), R¹⁶ represents a monovalent organic groupand a represents an integer of 0 to 5. In a case where a is 2 or more, aplurality of R¹⁶'s may be the same as or different from each other.Further, examples of the monovalent organic group of R¹⁶ include achained or cyclic alkyl group having 1 to 20 carbon atoms, and an arylgroup having 6 to 20 carbon atoms, which may have a substituent.

In the present invention, it is preferable that the specific polymerhaving the above-mentioned repeating unit A is an acrylic or methacrylicpolymer for a reason that liquid crystallinity is easily afforded andphase difference is easily expressed by a heating treatment afterirradiation with polarized ultraviolet rays.

Specific suitable examples of such a polymer include polymers havingrepeating units represented by Formulae (A-1) to (A-7).

Moreover, as long as the effect of the present invention is notinhibited, the specific polymer may have other repeating units, inaddition to the above-mentioned repeating unit A.

Examples of a monomer (radically polymerizable monomer) that forms suchother repeating units include an acrylic acid ester compound, amethacrylic acid ester compound, a maleimide compound, an acrylamidecompound, an acrylonitrile, a maleic anhydride, a styrene compound, anda vinyl compound.

In addition, in a case where the specific polymer has other repeatingunits, the content of the above-mentioned repeating unit A is preferably50% to 95% by mass, more preferably 60% to 90% by mass, and still morepreferably 70% to 90% by mass, with respect to 100% by mass of all therepeating units contained in the specific polymer. In the presentinvention, the content of each of the repeating units included in thespecific polymer is calculated based on the introduction amount (mass)of each of the monomers used so as to obtain each of the repeatingunits.

Furthermore, a method for synthesizing the specific polymer is notparticularly limited, and for example, the specific polymer can besynthesized by mixing a monomer that forms the above-mentioned repeatingunit A and a monomer that forms any other repeating units, andperforming polymerization using a radical polymerization initiator in anorganic solvent.

In addition, the weight-average molecular weight (Mw) of the specificpolymer is preferably 100,000 or less, more preferably 50,000 or less,and still more preferably 3,000 to 30,000.

Here, the weight-average molecular weight in the present invention is avalue measured by gel permeation chromatography (GPC) under theconditions shown below.

-   -   Solvent (eluent): Tetrahydrofuran (THF)    -   Device Name: TOSOH HLC-8320GPC    -   Column: 3 columns of TOSOH TSKgel Super HZM-H (4.6 mm×15 cm)        connected to each other are used.    -   Column temperature: 40° C.    -   Sample Concentration: 0.1% by mass    -   Flow rate: 1.0 ml/min    -   Calibration Curve: A calibration curve obtained from 7 samples        of TSK standard polystyrene Mw in a range of 2,800,000 to 1,050        (Mw/Mn=1.03 to 1.06) manufactured by TOSOH Corporation is used.

<Polymerizable Liquid Crystal Compound>

The specific composition used for the formation of the phase differencelayer contains a polymerizable liquid crystal compound having reciprocalwavelength dispersion.

Here, in the present specification, the polymerizable liquid crystalcompound having “reciprocal wavelength dispersion” means that in a casewhere an in-plane retardation (Re) value at a specific wavelength(visible light range) of a phase difference film manufactured usingprepared using the polymerizable liquid crystal compound is measured,the Re value becomes equal or higher as the measurement wavelength isincreased.

In addition, in the present specification, the “polymerizable liquidcrystal compound” refers to a liquid crystal compound having apolymerizable group. Further, the type of the polymerizable groupcontained in the polymerizable liquid crystal compound is notparticularly limited, and examples thereof include an acryloyl group, amethacryloyl group, a vinyl group, a styryl group, and an allyl group.

The type of the polymerizable liquid crystal compound is notparticularly limited and can be classified into a rod-like type(rod-like liquid crystal compound) and a disk-like type (disk-likeliquid crystal compound), depending on the shape. Each of the typesfurther includes a low molecular type and a high molecular type,respectively. The “high molecular type” generally refers to a polymerhaving a degree of polymerization of 100 or more (Kobunshi ButsuriSouten-i Dainamikusu (Polymer Physics and Phase Transition Dynamics),written by Masao Doi, p. 2, Iwanami Shoten, Publishers, 1992). In thepresent invention, any liquid crystal compound can be used. Two or morekinds of the rod-like liquid crystal compounds, two or more kinds of thedisk-like liquid crystal compounds, or a mixture of the rod-like liquidcrystal compound and the disk-like liquid crystal compound may be used.

Among those, the rod-like liquid crystal compound is preferably used. Areason therefor is that it is advantageous to make it easy to allow aphase difference film thus formed to function as a positive A-plate byhomogeneously (horizontally) aligning the rod-like liquid crystalcompound.

The polymerizable liquid crystal compound is not particularly limited aslong as it is capable of forming a film having reciprocal wavelengthdispersion as described above, and for example, the compound representedby General Formula (I) described in JP2008-297210A (in particular, thecompounds described in paragraph Nos. [0034] to [0039]), the compoundrepresented by General Formula (1) described in JP2010-084032A (inparticular, the compounds described in paragraph Nos. [0067] to [0073]),a liquid crystal compound represented by Formula (3) which will bedescribed later, or the like can be used.

In the present invention, from the viewpoint that the polymerizableliquid crystal compound has more excellent reciprocal wavelengthdispersion, a liquid crystal compound represented by Formula (3) ispreferable.

L¹-SP¹-A¹-D³-G¹-D¹-Ar-D²-G²-D⁴-A-SP²-L²  (3)

In Formula (3), D¹, D², D³, and D⁴ each independently represent a singlebond, —O—CO—, —C(═S)O—, —CR¹R²—, —CR¹R²—CR³R⁴—, —O—CR¹R²—,—CR¹R²—O—CR³R⁴—, —CO—O—CR¹R²—, —O—CO—CR¹R²—, —CR¹R²—O—CO—CR³R⁴—,—CR¹R²—CO—O—CR³R⁴—, —NR¹—CR²R³—, or —CO—NR¹—. R¹, R², R³, and R⁴ eachindependently represent a hydrogen atom, a fluorine atom, or an alkylgroup having 1 to 4 carbon atoms.

Moreover, in Formula (3), G¹ and G² each independently represent adivalent alicyclic hydrocarbon group having 5 to 8 carbon atoms, inwhich one or more of —CH₂-'s constituting the alicyclic hydrocarbongroup may be substituted with —O—, —S—, or —NH—.

Furthermore, in Formula (3), A¹ and A² each independently represent anaromatic ring having 6 or more carbon atoms, or a cycloalkane ringhaving 6 or more carbon atoms.

In addition, in Formula (3), SP¹ and SP² each independently represent asingle bond, a linear or branched alkylene group having 1 to 12 carbonatoms, or a divalent linking group in which one or more of —CH₂-'sconstituting the linear or branched alkylene group having 1 to 12 carbonatoms are substituted with —O—, —S—, —NH—, —N(Q)-, or —CO—, and Qrepresents a substituent.

Moreover, in Formula (3), L¹ and L² each independently represent amonovalent organic group, and at least one of L¹ or L² represents apolymerizable group. It should be noted that in a case where Ar is anaromatic ring represented by Formula (Ar-3) which will be describedlater, at least one of L¹ or L², or L³ or L⁴ in Formula (Ar-3) whichwill be described later represents a polymerizable group.

Furthermore, in Formula (3), Ar represents any one aromatic ringselected from the group consisting of groups represented by Formulae(Ar-1) to (Ar-5) which will be described later.

In Formula (3), as the divalent alicyclic hydrocarbon group having 5 to8 carbon atoms represented by each of G¹ and G², a 5- or 6-membered ringis preferable. Further, the alicyclic hydrocarbon group may be saturatedor unsaturated, but a saturated alicyclic hydrocarbon group ispreferable. With regard to the divalent alicyclic hydrocarbon grouprepresented by each of G¹ and G², reference can be made to, for example,the description in paragraph 0078 of JP2012-021068A, the contents ofwhich are incorporated herein by reference.

In Formula (3), examples of the aromatic ring having 6 or more carbonatoms represented by each of A¹ and A² include an aromatic hydrocarbonring such as a benzene ring, a naphthalene ring, an anthracene ring, anda phenanthroline ring; and an aromatic heterocyclic ring such as a furanring, a pyrrole ring, a thiophene ring, a pyridine ring, a thiazolering, and a benzothiazole ring. Among these, the benzene ring (forexample, a 1,4-phenyl group) is preferable.

In addition, in Formula (3), examples of the cycloalkane ring having 6or more carbon atoms represented by each of A¹ and A² include acyclohexane ring, a cycloheptane ring, a cyclooctane ring, acyclododecane ring, and a cyclodocosane ring. Among these, thecyclohexane ring (for example, a 1,4-cyclohexylene group) is preferable,and a trans-1,4-cyclohexylene group is more preferable.

In Formula (3), suitable examples of the linear or branched alkylenegroup having 1 to 12 carbon atoms represented by each of SP¹ and SP²include a methylene group, an ethylene group, a propylene group, and abutylene group.

In Formula (3), examples of the monovalent organic group represented byeach of L¹ and L² include an alkyl group, an aryl group, and aheteroaryl group. The alkyl group may be linear, branched, or cyclic,but is preferably linear. The number of carbon atoms of the alkyl groupis preferably 1 to 30, more preferably 1 to 20, and still morepreferably 1 to 10. Further, the aryl group may be monocyclic orpolycyclic, but is preferably monocyclic. The number of carbon atoms ofthe aryl group is preferably 6 to 25, and more preferably 6 to 10. Inaddition, the heteroaryl group may be monocyclic or polycyclic. Thenumber of heteroatoms constituting the heteroaryl group is preferably 1to 3. The heteroatom constituting the heteroaryl group is preferably anitrogen atom, a sulfur atom, or an oxygen atom. The number of carbonatoms of the heteroaryl group is preferably 6 to 18, and more preferably6 to 12. Incidentally, the alkyl group, the aryl group, or theheteroaryl group may be unsubstituted or may have a substituent.Examples of the substituent include the same ones as the substituentswhich may be contained in Y¹ in Formula (Ar-1).

On the other hand, in Formula (3), the polymerizable group representedby at least one of L¹ or L² is not particularly limited, but ispreferably a polymerizable group which is radically polymerizable orcationically polymerizable.

A generally known radically polymerizable group can be used as theradically polymerizable group, and suitable examples thereof include anacryloyl group and a methacryloyl group. In this case, it is known thatthe acryloyl group generally exhibits a fast polymerization rate, theacryloyl group is preferable from the viewpoint of an improvement inproductivity, but similarly, the methacryloyl group can also be used asthe polymerizable group.

In addition, a generally known cationically polymerizable group can beused as the cationically polymerizable group, and specific examplesthereof include an alicyclic ether group, a cyclic acetal group, acyclic lactone group, a cyclic thioether group, a spiroorthoester group,and a vinyloxy group. Among these, the alicyclic ether group or thevinyloxy group is preferable, and an epoxy group, an oxetanyl group, ora vinyloxy group is particularly preferable.

Particularly preferred examples of the polymerizable group include thefollowing groups.

In Formula (3), Ar represents any one aromatic ring selected from thegroup consisting of groups represented by Formulae (Ar-1) to (Ar-5). Inaddition, in Formulae (Ar-1) to (Ar-5), * represents a bonding positionto D¹ or D² in Formula (3).

Here, in Formula (Ar-1), Q¹ represents N or CH, Q² represents —S—, —O—,or —N(R⁵)—, R⁵ represents a hydrogen atom or an alkyl group having 1 to6 carbon atoms, and Y¹ represents an aromatic hydrocarbon group having 6to 12 carbon atoms or an aromatic heterocyclic group having 3 to 12carbon atoms, which may have a substituent.

Specific examples of the alkyl group having 1 to 6 carbon atomsrepresented by R⁵ include a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, asec-butyl group, a tert-butyl group, an n-pentyl group, and an n-hexylgroup.

Examples of the aromatic hydrocarbon group having 6 to 12 carbon atomsrepresented by Y¹ include an aryl group such as a phenyl group, a2,6-diethylphenyl group, and a naphthyl group.

Examples of the aromatic heterocyclic group having 3 to 12 carbon atomsrepresented by Y¹ include a heteroaryl group such as a thienyl group, athiazolyl group, a furyl group, and a pyridyl group.

In addition, examples of the substituent which may be contained in Y¹include an alkyl group, an alkoxy group, and a halogen atom.

As the alkyl group, for example, a linear, branched, or cyclic alkylgroup having 1 to 18 carbon atoms is preferable, an alkyl group having 1to 8 carbon atoms (for example, a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, asec-butyl group, a t-butyl group, and a cyclohexyl group) is morepreferable, an alkyl group having 1 to 4 carbon atoms is still morepreferable, and the methyl group or the ethyl group is particularlypreferable.

As the alkoxy group, for example, an alkoxy group having 1 to 18 carbonatoms is preferable, an alkoxy group having 1 to 8 carbon atoms (forexample, a methoxy group, an ethoxy group, an n-butoxy group, and amethoxyethoxy group) is more preferable, an alkoxy group having 1 to 4carbon atoms is still more preferable, and the methoxy group or theethoxy group is particularly preferable.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom, and an iodine atom, and among these, the fluorine atom orthe chlorine atom is preferable.

Moreover, in Formulae (Ar-1) to (Ar-5), Z¹, Z², and Z³ eachindependently represent a hydrogen atom, a monovalent aliphatichydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclichydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatichydrocarbon group having 6 to 20 carbon atoms, a halogen atom, a cyanogroup, a nitro group, —OR⁶, —NR⁷R⁸, or —SR⁹, R⁶ to R⁹ each independentlyrepresent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,and Z¹ and Z² may be bonded to each other to form an aromatic ring.

As the monovalent aliphatic hydrocarbon group having 1 to 20 carbonatoms, an alkyl group having 1 to 15 carbon atoms is preferable, analkyl group having 1 to 8 carbon atoms is more preferable, specifically,a methyl group, an ethyl group, an isopropyl group, a tert-pentyl group(1,1-dimethylpropyl group), a tert-butyl group, or a1,1-dimethyl-3,3-dimethyl-butyl group is still more preferable, and themethyl group, the ethyl group, or the tert-butyl group is particularlypreferable.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20carbon atoms include a monocyclic saturated hydrocarbon group such as acyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexylgroup, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, amethylcyclohexyl group, and an ethylcyclohexyl group; a monocyclicunsaturated hydrocarbon group such as a cyclobutenyl group, acyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, acyclooctenyl group, a cyclodecenyl group, a cyclopentadienyl group, acyclohexadienyl group, a cyclooctadienyl group, and a cyclodecadienylgroup; and a polycyclic saturated hydrocarbon group such as abicyclo[2.2.1]heptyl group, a bicyclo[2.2.2]octyl group, atricyclo[5.2.1.0^(2,6)]decyl group, a tricyclo[3.3.1.1^(3,7)]decylgroup, a tetracyclo[6.2.1.1^(3,6)0.0^(2,7)]dodecyl group, and anadamantyl group.

Specific examples of the monovalent aromatic hydrocarbon group having 6to 20 carbon atoms include a phenyl group, a 2,6-diethylphenyl group, anaphthyl group, and a biphenyl group, and an aryl group having 6 to 12carbon atoms (particularly a phenyl group) is preferable.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom, and an iodine atom, and among these, the fluorine atom,the chlorine atom, or the bromine atom is preferable.

On the other hand, specific examples of the alkyl group having 1 to 6carbon atoms represented by each of R⁶ to R⁸ include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a sec-butyl group, a tert-butyl group, an n-pentylgroup, and an n-hexyl group.

Moreover, in Formula (Ar-2) and (Ar-3), A³ and A⁴ each independentlyrepresent a group selected from the group consisting of —O—, —N(R¹⁰)—,—S—, and —CO—, and R¹⁰ represents a hydrogen atom or a substituent.

Examples of the substituent represented by R¹⁰ include the same ones asthe substituents which may be contained in Y¹ in Formula (Ar-1).

Furthermore, in Formula (Ar-2), X represents a hydrogen atom or anon-metal atom of Groups 14 to 16 to which a substituent may be bonded.

In addition, examples of the non-metal atom of Groups 14 to 16represented by X include an oxygen atom, a sulfur atom, a nitrogen atomhaving a substituent, and a carbon atom having a substituent, andspecific examples of the substituent include an alkyl group, an alkoxygroup, an alkyl substituted alkoxy group, a cyclic alkyl group, an arylgroup (for example, a phenyl group and a naphthyl group), a cyano group,an amino group, a nitro group, an alkylcarbonyl group, a sulfo group,and a hydroxyl group.

In addition, in Formula (Ar-3), D⁵ and D⁶ each independently represent asingle bond, —CO—O—, —O—CO—, —C(═S)O—, —CR¹R²—, —CR¹R²—CR³R⁴—,—O—CR¹R²—, —CR¹R²—O—CR³R⁴—, —CO—O—CR¹R²—, —O—CO—CR¹R²—,—CR¹R²—O—CO—CR³R⁴—, —CR¹R²—CO—O—CR³R⁴—, —NR¹—CR²R³—, or —CO—NR¹—. R¹,R², R³, and R⁴ each independently represent a hydrogen atom, a fluorineatom, or an alkyl group having 1 to 4 carbon atoms.

Moreover, in Formula (Ar-3), SP³ and SP⁴ each independently represent asingle bond, a linear or branched alkylene group having 1 to 12 carbonatoms, or a divalent linking group in which one or more of —CH₂-'sconstituting the linear or branched alkylene group having 1 to 12 carbonatoms are substituted with —O—, —S—, —NH—, —N(Q)-, or —CO—, and Qrepresents a substituent. Examples of the substituent include the sameones as the substituents which may be contained in Y¹ in Formula (Ar-1).

Furthermore, in Formula (Ar-3), L³ and L⁴ each independently represent amonovalent organic group, and at least one of L³ or L⁴, or L¹ or L² inFormula (3) represents a polymerizable group.

Examples of the monovalent organic group include the same ones as themonovalent organic groups described in L¹ and L² in Formula (3).

In addition, examples of the polymerizable group include the same onesas the polymerizable groups described in L¹ and L² in Formula (3).

Moreover, in Formulae (Ar-4) to (Ar-5), Ax represents an organic grouphaving 2 to 30 carbon atoms, which has at least one aromatic ringselected from the group consisting of an aromatic hydrocarbon ring andan aromatic heterocyclic ring.

Furthermore, in Formulae (Ar-4) to (Ar-5), Ay represents a hydrogenatom, an alkyl group having 1 to 12 carbon atoms, which may have asubstituent, or an organic group having 2 to 30 carbon atoms, which hasat least one aromatic ring selected from the group consisting of anaromatic hydrocarbon ring and an aromatic heterocyclic ring.

Here, the aromatic ring in each of Ax and Ay may have a substituent, andAx and Ay may be bonded to each other to form a ring.

In addition, Q³ represents a hydrogen atom, or an alkyl group having 1to 6 carbon atoms, which may have a substituent. Examples of Ax and Ayinclude those described in paragraphs [0039] to [0095] ofWO2014/010325A.

Furthermore, specific examples of the alkyl group having 1 to 6 carbonatoms represented by Q³ include a methyl group, an ethyl group, a propylgroup, an isopropyl group, an n-butyl group, an isobutyl group, asec-butyl group, a tert-butyl group, an n-pentyl group, and an n-hexylgroup, and examples of the substituent include the same ones as thesubstituents which may be contained in Y¹ in Formula (Ar-1).

Preferred examples of the liquid crystal compound represented by Formula(3) are shown below, but are not limited to these liquid crystalcompounds. Further, the 1,4-cyclohexylene groups in the followingformulae are all trans-1,4-cyclohexylene groups

No Y1 n II-1-1

6 II-1-2

6 II-1-3

6 II-1-4

6 II-1-5

6 II-1-6

11 II-1-7

8 II-1-8

4 II-1-9

6 II-1-10

6 II-1-11

6 II-1-12

6 II-1-13

6 II-1-14

6 II-1-15

6

No X R1 II-2-1

H II-2-2

H II-2-3

H II-2-4

H II-2-5

CH₃ II-2-6

II-2-7 S H

In addition, in the formulae, “*” represents a bonding position.

In addition, a group adjacent to the acryloyloxy group in FormulaeII-2-8 and II-2-9 represents a propylene group (a group in which amethyl group is substituted with an ethylene group), and a mixture ofpositional isomers in which the positions of the methyl groups aredifferent.

No Ax Ay Q2 II- 3-1

H H II- 3-2

H H II- 3-3

H H II- Ph Ph H 3-4 II- 3-5

H H II- 3-6

H H II- 3-7

CH₃ H II- 3-8

C₄H₉ H II- 3-9

C₆H₉ H II- 3-10

H II- 3-11

H II- 3-12

CH₂CN H II- 3-13

H II- 3-14

H II- 3-15

CH₂CH₂OH H II- 3-16

H H II- 3-17

CH₃CF₃ H II- 3-18

H CH₃ II- 3-19

H II- 3-20

H II- 3-21

H II- 3-22

H II- 3-23

H II- 3-24

H II- 3-25

C₆H₁₃ H

No Ax Ay Q2 II- 3-30

H H II- 3-31

H H II- 3-32

H H II- Ph Ph H 3-33 II- 3-34

H H II- 3-35

H H II- 3-36

CH₃ H II- 3-37

C₄H₉ H II- 3-38

C₆H₉ H II- 3-39

H II- 3-40

H II- 3-41

CH₂CN H II- 3-42

H II- 3-43

H II- 3-44

CH₂CH₂OH H II- 3-45

H H II- 3-46

CH₃CF₃ H II- 3-47

H CH₃ II- 3-48

H II- 3-49

H II- 3-50

H II- 3-51

H II- 3-52

H II- 3-53

H II- 3-54

C₆H₁₃ H

In the present invention, for a reason that the reciprocal wavelengthdispersion is further improved, the liquid crystal compound representedby Formula (3) is preferably a liquid crystal compound in which A¹ andA² in Formula (3) are each independently a cycloalkane ring having 6 ormore carbon atoms, and more preferably a liquid crystal compound inwhich A¹ and A² in Formula (3) each independently represent acycloalkane ring having 6 or more carbon atoms and D³ and D⁴ in Formula(3) both represent a single bond.

Suitable examples of these liquid crystal compounds include compoundsrepresented by Formulae (3-1) to (3-12), and specifically the compoundshaving side chain structures shown in Tables 1 and 2 below as K (sidechain structure) in Formulae (3-1) to (3-12).

In addition, in Tables 1 and 2 below, “*” shown in the side chainstructure of K represents a bonding position to the aromatic ring.

In addition, in the side chain structures shown in 1-2 in Table 1 belowand 2-2 in Table 2 below, each of groups adjacent to the acryloyloxygroup and the methacryloyl group represents a propylene group (a groupin which a methyl group is substituted with an ethylene group), and amixture of positional isomers in which the positions of the methylgroups are different.

TABLE 1 K (Side chain structure) 1-1

1-2

1-3

1-4

1-5

1-6

1-7

1-8

1-9

1-10

1-11

1-12

1-13

TABLE 2 K (Side chain structure) 2-1

2-2

2-3

2-4

2-5

2-6

2-7

2-8

2-9

2-10

2-11

2-12

2-13

<Polymerizable Compound>

The specific composition used for the formation of the phase differencelayer may include a polymerizable compound, in addition to theabove-mentioned liquid crystalline compound having reciprocal wavelengthdispersion.

Here, the polymerizable group contained in the polymerizable compound isnot particularly limited, and examples thereof include an acryloylgroup, a methacryloyl group, a vinyl group, a styryl group, and an allylgroup. Among these, the acryloyl group or the methacryloyl group ispreferably contained.

For a reason that the light resistance of a phase difference layerformed is further improved, the polymerizable compound is preferablyanother polymerizable compound having 2 to 4 polymerizable groups, andmore preferably another polymerizable compound having 2 polymerizablegroups.

Examples of such another polymerizable compound include the compoundsrepresented by Formulae (M1), (M2), and (M3) described in paragraphs[0030] to [0033] of JP2014-077068A, and more specifically, specificexamples of the polymerizable compound include the compounds describedin paragraphs [0046] to [0055] of the same publication.

<Polymerization Initiator>

The specific composition used for the formation of a phase differencelayer preferably contains a polymerization initiator.

As the polymerization initiator used, a photopolymerization initiatorcapable of initiating a polymerization reaction by irradiation withultraviolet rays (UV) is preferable.

Examples of the photopolymerization initiator include α-carbonylcompounds (described in each of the specifications of U.S. Pat. Nos.2,367,661A and 2,367,670A), acyloin ethers (described in U.S. Pat. No.2,448,828A), aromatic acyloin compounds substituted with α-hydrocarbon(described in U.S. Pat. No. 2,722,512A), polynuclear quinone compounds(described in each of the specifications of U.S. Pat. Nos. 3,046,127Aand 2,951,758A), a combination of a triarylimidazole dimer and ap-aminophenyl ketone (described in U.S. Pat. No. 3,549,367A), acridineand phenazine compounds (described in JP1985-105667A (JP-S60-105667A)and U.S. Pat. No. 4,239,850A), oxadiazole compounds (described in U.S.Pat. No. 4,212,970A), and acylphosphine oxide compounds (described inJP1988-040799B (JP-S63-040799B), JP1993-029234B (JP-H05-029234B),JP1998-095788A (JP-H 10-095788A), and JP1998-029997A (JP-H10-029997A)).

<Solvent>

It is preferable that the specific composition used for the formation ofa phase difference layer contains a solvent from the viewpoints ofworkability for forming a phase difference layer, and the like.

Specific examples of the solvent include ketones (for example, acetone,2-butanone, methyl isobutyl ketone, and cyclohexanone), ethers (forexample, dioxane and tetrahydrofuran), aliphatic hydrocarbons (forexample, hexane), alicyclic hydrocarbons (for example, cyclohexane),aromatic hydrocarbons (for example, toluene, xylene, andtrimethylbenzene), halogenated carbons (for example, dichloromethane,dichloroethane, dichlorobenzene, and chlorotoluene), esters (forexample, methyl acetate, ethyl acetate, and butyl acetate), water,alcohols (for example, ethanol, isopropanol, butanol, and cyclohexanol),cellosolves (for example, methyl cellosolve and ethyl cellosolve),cellosolve acetates, sulfoxides (for example, dimethyl sulfoxide), andamides (for example, dimethylformamide and dimethylacetamide), and thesemay be used singly or in combination of two or more kinds thereof.

The phase difference plate of the embodiment of the present inventionhas a phase difference layer formed from the above-mentioned specificcomposition. In addition, a method for forming the phase differencelayer will be described in detail with reference to the method forproducing a phase difference plate of an embodiment of the presentinvention which will be described later.

In the present invention, the content of the specific polymer in thephase difference layer is preferably 5% to 40% by mass, more preferably5% to 30% by mass, and still more preferably 5% to 20% by mass. Inaddition, the specific polymers may be used singly or in combination oftwo or more kinds thereof. In a case where two or more kinds of thespecific polymers are used in combination, it is preferable that thetotal amount thereof satisfies the content.

In addition, the content of the polymerizable liquid crystal compoundhaving reciprocal wavelength dispersion in the phase difference layer ispreferably 50% to 99% by mass, more preferably 60% to 97% by mass, andstill more preferably 70% to 95% by mass. Further, the polymerizableliquid crystal compounds having reciprocal wavelength dispersion may beused singly or in combination of two or more kinds thereof. In a casewhere two or more kinds of the polymerizable liquid crystal compoundshaving reciprocal wavelength dispersion are used in combination, it ispreferable that the total amount thereof satisfies the content.

Furthermore, in the present invention, the thickness of the phasedifference layer is not particularly limited, but is preferably 10 μm orless, and more preferably 5 μm or less. The lower limit of the thicknessis not particularly limited, but is generally 10 nm or more, andpreferably 50 nm or more.

In addition, the phase difference layer is preferably a monolayerstructure.

In the present invention, for a reason that a black tint viewing angleis improved, it is preferable that the phase difference layer satisfiesFormula (I).

Re(450)≤Re(550)≤Re(650)  (1)

Here, in Formula (I), Re(450) represents an in-plane retardation valuemeasured at a wavelength of 450 nm, Re(550) represents an in-planeretardation value measured at a wavelength of 550 nm, and Re(650)represents an in-plane retardation value measured at a wavelength of 650nm. Further, in the present specification, the measurement wavelength isdefined as 550 nm unless the measurement wavelength for retardationvalue is otherwise specified.

In addition, the values of the in-plane retardation and thethickness-direction retardation refer to values measured with light atthe measurement wavelength using AxoScan OPMF-1 (manufactured by OptoScience, Inc.).

Specifically, by inputting the average refractive index ((Nx+Ny+Nz)/3)and the film thickness (d (μm)) to AxoScan OPMF-1, it is possible tocalculate:

Slow axis direction (°)

Re(λ)=R0(λ)

Rth(λ)=((nx+ny)/2−nz)×d.

In addition, R0(λ) is expressed in a numerical value calculated withAxoScan OPMF-1, but means Re(λ).

Moreover, in the present invention, for a reason that linearly polarizedlight at a wavelength of 550 nm having high human visual sensitivity isaccurately converted to circularly polarized light, the Re(550) of thephase difference layer is preferably 100 to 180 nm, and more preferably120 to 150 nm.

Furthermore, in the present invention, for a reason that the black tintin the oblique direction is good, the Rth(550) of the phase differencelayer is preferably −10 to 10 nm, and more preferably −5 to 5 nm.

In addition, in the present invention, for a reason that 120 to 150 nmof the Re(550) and −5 to 5 nm of the Rth(550) are both satisfied, it ispreferable that the phase difference layer satisfies a refractive indexrelationship represented by Formula (II).

nx>nz>ny  (II)

Here, in Formula (II) and Formula (III) which will be described later,nx is a refractive index in a direction in which a refractive index ismaximum in a plane (slow axis), ny is a refractive index in a directionin which a refractive index is minimum in a plane (fast axis), and nzrepresents a refractive index in a thickness direction perpendicular tonx and ny.

In addition, the refractive indices nx, ny, and nz are measured using anAbbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) and asodium lamp (λ=589 nm) as a light source. In addition, in a case ofmeasuring wavelength dependency, the wavelength dependency can bemeasured with a multi-wavelength Abbe refractometer DR-M2 (manufacturedby Atago Co., Ltd.) in combination with an interference filter.

Moreover, in the present invention, for a reason that 120 to 150 nm ofthe Re(550) and −5 to 5 nm of the Rth(550) are both satisfied, it ispreferable that the phase difference layer satisfies a refractive indexrelationship represented by Formula (III).

0.4<(nx−nz)/(nx−ny)<0.6  (III)

[Transparent Support]

The phase difference plate of the embodiment of the present inventionmay have a transparent support that supports the above-mentioned phasedifference layer.

Here, a term “transparent” as mentioned in the present inventionindicates that the transmittance of visible light is 60% or more,preferably 80% or more, and particularly preferably 90% or more.

Examples of such a transparent support include a glass substrate and apolymer film.

Examples a material for the polymer film include cellulose-basedpolymers; acrylic polymers having an acrylic acid ester polymer such aspolymethyl methacrylate and a lactone ring-containing polymer;thermoplastic norbornene-based polymers; polycarbonate-based polymers;polyester-based polymers such as polyethylene terephthalate andpolyethylene naphthalate; styrene-based polymers such as polystyrene andan acrylonitrile-styrene copolymer (AS resin); polyolefin-based polymerssuch as polyethylene, polypropylene, and an ethylene-propylenecopolymer; vinyl chloride-based polymers; amide-based polymers such asnylon and aromatic polyamide; imide-based polymers; sulfone-basedpolymers; polyether sulfone-based polymers; polyether ether ketone-basedpolymers; polyphenylene sulfide-based polymers; vinylidenechloride-based polymers; vinyl alcohol-based polymers; vinylbutyral-based polymers; acrylate-based polymers; polyoxymethylene-basedpolymers; epoxy-based polymers; and polymers containing a mixture ofthese polymers.

The thickness of the transparent support is not particularly limited,but is preferably 5 to 200 μm, more preferably 10 to 100 μm, and stillmore preferably 20 to 90 μm.

[Method for Producing Phase Difference Plate]

The method for producing a phase difference plate of the embodiment ofthe present invention, used for the manufacture of the phase differenceplate of the embodiment of the present invention, has an applying stepof applying a specific composition containing the above-mentionedspecific polymer and a polymerizable liquid crystal compound onto theabove-mentioned transparent support to form a coating film, anirradiating step of performing irradiation with polarized ultravioletrays from a direction perpendicular to the coating film, and a heatingstep of subjecting the coating film after the irradiating step to aheating treatment to form a phase difference layer.

[Applying Step]

An applying method in the applying step is not particularly limited, andexamples thereof include a spin coating method, an air knife coatingmethod, a curtain coating method, a roller coating method, a wire barcoating method, a gravure coating method, and a die coating method.

In addition, the coating amount is preferably controlled such that aphase difference layer having a desired thickness can be produced.

[Irradiating Step]

The irradiating step is a step of irradiating the coating film formed bythe applying step with polarized ultraviolet rays from a directionperpendicular to the coating film.

Examples of a method for performing irradiation with polarizedultraviolet rays include a method using a polarizing plate (for example,an iodine polarizing plate, a dichroic dye polarizing plate, and a wiregrid polarizing plate); a method using a prism-based element (forexample, a Glan-Thompson prism) or a reflection type polarizer utilizingthe angle of polarization (Brewstar's angle); and a method using lightemitted from a laser light source having polarized light.

A light source used for irradiation with ultraviolet rays is notparticularly limited as long as it is a light source that generatesultraviolet rays, and for example, a low-pressure mercury lamp, anintermediate-pressure mercury lamp, a high-pressure mercury lamp, anultrahigh-pressure mercury lamp, a carbon-arc lamp, a metal halide lamp,a xenon lamp, or the like can be used.

The light irradiation dose is preferably 300 to 30,000 mJ/cm², and morepreferably 500 to 15,000 mJ/cm².

By controlling the light irradiation dose to change the alignment stateof the photo-alignment group in the repeating unit A contained in thespecific polymer, it is possible to control an Nz factor, that is,(nx−nz)/(nx−ny) of the phase difference layer.

[Heating Step]

The heating step is a step of subjecting the coating film after theirradiating step to a heating treatment to form a phase differencelayer.

In the present invention, the heating temperature in the heating step ispreferably 50° C. or higher, more preferably 100° C. to 200° C., andstill more preferably 120° C. to 180° C.

In addition, the heating time is preferably 30 seconds to 10 minutes,more preferably 1 minute to 10 minutes, and still more preferably 2minutes to 8 minutes.

[Organic EL Display Device]

The organic EL display device of an embodiment of the present inventionhas the phase difference plate of the embodiment of the presentinvention and an organic EL light emitting element.

Suitable examples of such an organic EL display device include an aspectof an organic EL display panel which has a polarizer, the phasedifference plate of the embodiment of the present invention, and anorganic EL display panel in this order from the viewing side.

[Polarizer]

The polarizer is not particularly limited as long as it is a memberhaving a function of converting light into specific linearly polarizedlight, and an absorption type polarizer and a reflection type polarizer,which are known in the related art, can be used.

An iodine-based polarizer, a dye-based polarizer using a dichroic dye, apolyene-based polarizer, or the like is used as the absorption typepolarizer. As the iodine-based polarizer and the dye-based polarizer,there are a coating type polarizer and a stretching type polarizer, bothof which can be applied, but a polarizer prepared by allowing polyvinylalcohol to adsorb iodine or a dichroic dye and performing stretching ispreferable.

In addition, examples of a method for obtaining a polarizer byperforming stretching and dyeing in a state of a laminated film in whicha polyvinyl alcohol layer is formed on a base material include themethods disclosed in JP5048120B, JP5143918B, JP4691205B, JP4751481B, andJP4751486B, and known technologies related to these polarizers can alsobe preferably used.

A polarizer in which thin films having different birefringence arelaminated, a wire grid type polarizer, a polarizer in which acholesteric liquid crystal having a selective reflection range and a ¼wavelength plate are combined, or the like is used as the reflectiontype polarizer.

Among these, from the viewpoint that the adhesiveness is more excellent,a polarizer including a polyvinyl alcohol-based resin (a polymerincluding —CH₂—CHOH— as a repeating unit, in particular, at least oneselected from the group consisting of polyvinyl alcohol and anethylene-vinyl alcohol copolymer) is preferable.

The thickness of the polarizer is not particularly limited, but ispreferably 3 μm to 60 μm, more preferably 5 μm to 30 μm, and still morepreferably 5 μm to 15 μm.

[Organic EL Display Panel]

The organic EL display panel is a member which forms a light emittinglayer or a plurality of organic compound thin films including the lightemitting layer between a pair of electrodes, that is, an anode and acathode, and may have a hole injecting layer, a hole transporting layer,an electron injecting layer, an electron transporting layer, aprotective layer, or the like, in addition to the light emitting layer,and each of these layers may comprise different functions. Each ofvarious materials can be used to form each of the layers.

EXAMPLES

Hereinafter, the present invention will be described in more detail withreference to Examples. The materials, the amounts to materials used, theratios, the treatment details, the treatment procedure, and the likeshown in the following Examples can be modified as appropriate while notdeparting from the spirit of the present invention. Therefore, the scopeof the present invention should not be restrictively interpreted by thefollowing Examples.

Example 1

[Manufacture of Phase Difference Plate 1 Having Reciprocal WavelengthDispersion]

<Preparation of Composition 1 for Phase Difference Layer 1>

The following composition was dissolved to prepare a composition 1 for aphase difference layer 1.

Composition 1 for phase difference layer 1 The following polymer P-1  4parts by mass The following polymerizable liquid crystal compound 16parts by mass L-1 Chloroform 80 parts by mass P-1

L-1

<Manufacture of Phase Difference Layer 1>

The composition 1 for a phase difference layer 1 was applied onto aglass substrate using a spin coater, and the film was dried and thenirradiated with ultraviolet rays in the atmosphere using an air-coolingmetal halide lamp (manufactured by Eyegraphics Co., Ltd.) from thecoating surface side. At this time, a wire grid polarizer (ProFluxPPL02, manufactured by Moxtek, Inc.) was set to be in parallel with thecoating surface and exposure was performed from a directionperpendicular to the coating surface. In addition, the illuminance ofultraviolet rays used herein was set to 100 mW/cm² in the UV-A region(integration at the wavelengths of 380 nm to 320 nm) and the irradiationdose was set to 1,000 mJ/cm² in the UV-A region.

Subsequently, the coating film was heated at 150° C. to 5 minutes andthen cooled to room temperature (23° C.) to manufacture a phasedifference plate 1. The film thickness of the obtained phase differencelayer 1 was 3.5 μm.

Example 2

[Manufacture of Phase Difference Plate 2 Having Reciprocal WavelengthDispersion]

A phase difference plate 2 of Example 2 was manufactured by the samemethod as in Example 1, except that the following polymerizable liquidcrystal compound L-2 was used instead of the polymerizable liquidcrystal compound L-1. The film thickness of the phase difference layerwas 3.5 μm.

Example 3

[Manufacture of Phase Difference Plate 3 Having Reciprocal WavelengthDispersion]

A phase difference plate 3 of Example 3 was manufactured by the samemethod as in Example 2, except that a polymer P-2 was used instead ofthe polymer P-1. The film thickness of the phase difference layer was3.5 μm.

Example 4

[Manufacture of Phase Difference Plate 4 Having Reciprocal WavelengthDispersion]

A phase difference plate 4 of Example 4 was manufactured by the samemethod as in Example 2, except that a polymer P-3 was used instead ofthe polymer P-1. The film thickness of the phase difference layer was3.5 μm.

Comparative Example 1

[Manufacture of Phase Difference Plate 5 Having Forward WavelengthDispersion]

A phase difference plate 5 of Comparative Example 1 was manufactured bythe same method as in Example 1, except that 19 parts by mass of thefollowing high molecular compound 1 described in Example 1 ofJP2016-080942A was used instead of the polymer P-1, 1 part by mass ofthe following rod-like liquid crystal compound 1 described in Example 1of JP2016-080942A was used instead of the polymerizable liquid crystalcompound L-1, and heating after the irradiation was not performed. Thefilm thickness of the phase difference layer was adjusted to 1.0 μm.

High Molecular Compound 1 (Weight-Average Molecular Weight: 24,000)

Rod-Like Liquid Crystal Compound 1

[Evaluation]

<Optical Characteristics>

With regard to each of the phase difference plates manufactured inExamples and Comparative Examples as described above, Re(550), Rth(550),Re(450)/Re(550), Re(650)/Re(550), nx, ny, and nz were evaluated by theabove-mentioned methods. The evaluation results are shown in Table 3.

<Evaluation of Light Resistance>

With regard to each of the phase difference plates manufactured inExamples and Comparative Examples as described above, xenon light wasirradiated from the phase difference plate side through an ultravioletblocking film at 250,000 Lx for 200 hours under the conditions of 60° C.and a relative humidity of 50%, using a super xenon weather meter (SX-75manufactured by Suga Test Instruments Co., Ltd.). A change in Re after alapse of 1 hour in a dark place at room temperature was measured. Theevaluation results are shown in Table 3.

A: The change in Re is less than 5%.

B: The change in Re is 5% or more and less than 20%.

C: The change in Re is 20% or more.

TABLE 3 Polymerizable liquid crystal Re (450)/ Re (650)/ Refractiveindex (nx − Light Polymer compound Re (nm) Rth (nm) Re (550) Re (550) nxny nz nz)/(nx − ny) resistance Example 1 P-1 L-1 155 0 0.90 1.01 1.561.52 1.54 0.5 A Example 2 P-1 L-2 105 0 0.80 1.05 1.55 1.52 1.54 0.5 AExample 3 P-2 L-2 140 0 0.85 1.03 1.56 1.52 1.54 0.5 A Example 4 P-3 L-2105 0 0.80 1.05 1.55 1.52 1.54 0.5 A Comparative High Rod-like liquid120 0 1.22 0.96 1.66 1.54 1.60 0.5 C Example 1 molecular crystalcompound 1 compound 1

From the results shown in Table 3, it could be seen that in a case ofusing a phase difference layer formed from a composition containing apolymer having a repeating unit A including an azo group as aphoto-alignment group, birefringent properties and biaxial propertiesare expressed upon irradiation with polarized light, but the wavelengthdispersion is forward dispersibility and the light resistance is alsopoor (Comparative Example 1).

In contrast, it could be seen that in a case of using a phase differencelayer formed from a composition containing a polymer having a repeatingunit A including a photo-alignment group including a double bondstructure of C═C or C═N and a polymerizable liquid crystal compoundhaving reciprocal wavelength dispersion, reciprocal wavelengthdispersion can be realized in any case (Examples 1 to 4). In addition,it could also be seen that a phase difference layer thus manufacturedexpresses biaxial birefringent properties, and thus, the lightresistance is also excellent.

What is claimed is:
 1. A phase difference plate for an organic ELdisplay device, comprising a phase difference layer formed from acomposition containing a polymer having a repeating unit A including aphoto-alignment group and a polymerizable liquid crystal compound havingreciprocal wavelength dispersion, wherein the photo-alignment groupincludes a double bond structure of C═C or C═N.
 2. The phase differenceplate for an organic EL display device according to claim 1, wherein thepolymerizable liquid crystal compound having reciprocal wavelengthdispersion is a liquid crystal compound represented by Formula (3),L¹-SP¹-A¹-D³-G¹-D¹-Ar-D²-G²-D⁴-A²-SP²-L²  (3) in Formula (3), D¹, D²,D³, and D⁴ each independently represent a single bond, —O—CO—, —C(═S)O—,—CR¹R²—, —CR¹R²—CR³R⁴—, —O—CR¹R²—, —CR¹R²—O—CR³R⁴—, —CO—O—CR¹R²—,—O—CO—CR¹R²—, —CR¹R²—O—CO—CR³R⁴—, —CR¹R²—CO—O—CR³R⁴—, —NR¹—CR²R³—, or—CO—NR¹—, and R¹, R², R³, and R⁴ each independently represent a hydrogenatom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms, G¹and G² each independently represent a divalent alicyclic hydrocarbongroup having 5 to 8 carbon atoms, in which one or more of —CH2-'sconstituting the alicyclic hydrocarbon group may be substituted with—O—, —S—, or —NH—, A¹ and A² each independently represent an aromaticring having 6 or more carbon atoms or a cycloalkane ring having 6 ormore carbon atoms, SP¹ and SP² each independently represent a singlebond, a linear or branched alkylene group having 1 to 12 carbon atoms,or a divalent linking group in which one or more of —CH₂-'s constitutingthe linear or branched alkylene group having 1 to 12 carbon atoms aresubstituted with —O—, —S—, —NH—, —N(Q)-, or —CO—, and Q represents asubstituent, L¹ and L² each independently represent a monovalent organicgroup, and at least one of L¹ or L² represents a polymerizable group,provided that in a case where Ar is an aromatic ring represented byFormula (Ar-3), at least one of L¹ or L², or L³ or L⁴ in Formula (Ar-3)represents a polymerizable group, and Ar represents any one aromaticring selected from the group consisting of groups represented byFormulae (Ar-1) to (Ar-5),

in Formulae (Ar-1) to (Ar-5), * represents a bonding position to D¹ orD², Q¹ represents N or CH, Q² represents —S—, —O—, or —N(R⁵)—, and R⁵represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms,Y¹ represents an aromatic hydrocarbon group having 6 to 12 carbon atomsor an aromatic heterocyclic group having 3 to 12 carbon atoms, each ofwhich may have a substituent, Z¹, Z², and Z³ each independentlyrepresent a hydrogen atom, a monovalent aliphatic hydrocarbon grouphaving 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon grouphaving 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon grouphaving 6 to 20 carbon atoms, a halogen atom, a cyano group, a nitrogroup, —OR⁶, —NR⁷R⁸, or —SR⁹, R⁶ to R⁹ each independently represent ahydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Z¹ andZ² may be bonded to each other to form an aromatic ring, A³ and A⁴ eachindependently represent a group selected from the group consisting of—O—, —N(R¹⁰)—, —S—, and —CO—, and R¹⁰ represents a hydrogen atom or asubstituent, X represents a hydrogen atom or a non-metal atom of Groups14 to 16 to which a substituent may be bonded, D⁵ and D⁶ eachindependently represent a single bond, —CO—O—, —C(═S)O—, —CR¹R²⁻,—CR¹R²—CR³R—, —O—CR¹R²—, —CR¹R²—O—CR³R⁴—, —CO—O—CR¹R²—, —O—CO—CR¹R²—,—CR¹R²—O—CO—CR³R⁴—, —CR¹R²—CO—O—CR³R⁴—, —NR¹—CR²R³—, or —CO—NR¹—, andR¹, R², R³, and R⁴ each independently represent a hydrogen atom, afluorine atom, or an alkyl group having 1 to 4 carbon atoms, SP³ and SP⁴each independently represent a single bond, a linear or branchedalkylene group having 1 to 12 carbon atoms, or a divalent linking groupin which one or more of —CH₂-'s constituting the linear or branchedalkylene group having 1 to 12 carbon atoms are substituted with —O—,—S—, —NH—, —N(Q)-, or —CO—, and Q represents a substituent. L³ and L⁴each independently represent a monovalent organic group, and at leastone of L³ or L⁴, or L¹ or L² in Formula (3) represents a polymerizablegroup, Ax represents an organic group having 2 to 30 carbon atoms, whichhas at least one aromatic ring selected from the group consisting of anaromatic hydrocarbon ring and an aromatic heterocyclic ring, Ayrepresents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms,which may have a substituent, or an organic group having 2 to 30 carbonatoms, which has at least one aromatic ring selected from the groupconsisting of an aromatic hydrocarbon ring and an aromatic heterocyclicring, the aromatic ring in each of Ax and Ay may have a substituent, andAx and Ay may be bonded to each other to form a ring, and Q³ representsa hydrogen atom, or an alkyl group having 1 to 6 carbon atoms, which mayhave a substituent.
 3. The phase difference plate for an organic ELdisplay device according to claim 1, wherein the photo-alignment groupis a cinnamate group or a chalcone group.
 4. The phase difference platefor an organic EL display device according to claim 2, wherein thephoto-alignment group is a cinnamate group or a chalcone group.
 5. Thephase difference plate for an organic EL display device according toclaim 1, wherein the polymer is an acrylic or methacrylic polymer. 6.The phase difference plate for an organic EL display device according toclaim 2, wherein the polymer is an acrylic or methacrylic polymer. 7.The phase difference plate for an organic EL display device according toclaim 1, wherein the phase difference layer satisfies Formula (I),Re(450)≤Re(550)≤Re(650)  (I) in Formula (I), Re(450) represents anin-plane retardation value measured at a wavelength of 450 nm, Re(550)represents an in-plane retardation value measured at a wavelength of 550nm, and Re(650) represents an in-plane retardation value measured at awavelength of 650 nm.
 8. The phase difference plate for an organic ELdisplay device according to claim 2, wherein the phase difference layersatisfies Formula (I),Re(450)≤Re(550)≤Re(650)  (I) in Formula (I), Re(450) represents anin-plane retardation value measured at a wavelength of 450 nm, Re(550)represents an in-plane retardation value measured at a wavelength of 550nm, and Re(650) represents an in-plane retardation value measured at awavelength of 650 nm.
 9. The phase difference plate for an organic ELdisplay device according to claim 1, wherein the phase difference layeris a layer indicating an in-plane retardation value measured at awavelength of 550 nm of 100 to 180 nm.
 10. The phase difference platefor an organic EL display device according to claim 2, wherein the phasedifference layer is a layer indicating an in-plane retardation valuemeasured at a wavelength of 550 nm of 100 to 180 nm.
 11. The phasedifference plate for an organic EL display device according to claim 1,wherein the phase difference layer is a layer indicating athickness-direction retardation value measured at a wavelength of 550 nmof −10 to 10 nm.
 12. The phase difference plate for an organic ELdisplay device according to claim 2, wherein the phase difference layeris a layer indicating a thickness-direction retardation value measuredat a wavelength of 550 nm of −10 to 10 nm.
 13. The phase differenceplate for an organic EL display device according to claim 1, wherein thephase difference layer satisfies a refractive index relationshiprepresented by Formula (II),nx>nz>ny  (II) in Formula (II), nx is a refractive index in a directionin which a refractive index is maximum in a plane, ny is a refractiveindex in a direction in which a refractive index is minimum in a plane,and nz represents a refractive index in a thickness directionperpendicular to nx and ny.
 14. The phase difference plate for anorganic EL display device according to claim 2, wherein the phasedifference layer satisfies a refractive index relationship representedby Formula (II),nx>nz>ny  (II) in Formula (II), nx is a refractive index in a directionin which a refractive index is maximum in a plane, ny is a refractiveindex in a direction in which a refractive index is minimum in a plane,and nz represents a refractive index in a thickness directionperpendicular to nx and ny.
 15. The phase difference plate for anorganic EL display device according to claim 1, wherein the phasedifference layer satisfies Formula (III),0.4<(nx−nz)/(nx−ny)<0.6  (III) in Formula (III), nx is a refractiveindex in a direction in which a refractive index is maximum in a plane,ny is a refractive index in a direction in which a refractive index isminimum in a plane, and nz represents a refractive index in a thicknessdirection perpendicular to nx and ny.
 16. The phase difference plate foran organic EL display device according to claim 1, wherein the phasedifference layer is a monolayer structure.
 17. An organic EL displaydevice comprising: the phase difference plate for an organic EL displaydevice according to claim 1; and an organic EL light emitting element.18. An organic EL display device comprising: the phase difference platefor an organic EL display device according to claim 2; and an organic ELlight emitting element.
 19. A method for producing a phase differenceplate, used for the manufacture of the phase difference plate for anorganic EL display device according to claim 1, the method comprising:an applying step of applying a composition containing a polymer having arepeating unit A including a photo-alignment group including a doublebond structure of C═C or C═N and a polymerizable liquid crystal compoundhaving reciprocal wavelength dispersion onto a transparent support toform a coating film; an irradiating step of performing irradiation withpolarized ultraviolet rays from a direction perpendicular to the coatingfilm; and a heating step of subjecting the coating film to a heatingtreatment after the irradiating step to form a phase difference layer.20. A method for producing a phase difference plate, used for themanufacture of the phase difference plate for an organic EL displaydevice according to claim 2, the method comprising: an applying step ofapplying a composition containing a polymer having a repeating unit Aincluding a photo-alignment group including a double bond structure ofC═C or C═N and a polymerizable liquid crystal compound having reciprocalwavelength dispersion onto a transparent support to form a coating film;an irradiating step of performing irradiation with polarized ultravioletrays from a direction perpendicular to the coating film; and a heatingstep of subjecting the coating film to a heating treatment after theirradiating step to form a phase difference layer.